Oscillation generator



To all whom it may concern. I

EDWARD OQSc IVEN, OF NEw YORK, N.'Y., AssIeNoE 'ro' WESTERN ELECTRIC com- PANY, mcoaroaarnn, OE NEW YORK, N. Y., a CORPORATION on NEW YORK.

OscILLarIoN GENERATOR.

Application filed June 4,

Be it known that I, EDWARD ScRIvEN, a citizen of the United States, residing at.

New York, in the county of New York and 7 State of New York, have invented certain new and useful Improvements'in Oscillation Generators, of which the following is a full, clear, concise, and exact description. This invention relates to oscillation generators, and particularly to vacuum tube oscillators.

It is well known in the art that a vacuum tube repeater of the audion type, for example, may'be made to oscillate by providing a feed-back connection from theoutput to the input circuit of the device,.,and by pro- A vidingga' condenser suitably placed in the 7 tube circuits for tuning to the desired freoscillator, such as the impedance of the vacquency. One type of. such a generator is described by Hartley in his Unlted States Patent 1,356,763, for oscillation generators, patented October 26, 1920. The output, however, from such a generator is not constant for a given. setting ofth condenser and the feed-back connectioni'f *diipends upon the electrical valu ifi 'bf the other elements of the uum tube and "the voltage of thedirect current-source;

The object of this invention is 'to provide means for generating oscillations, the intensity of which is independent of small changes in the impedance between the output 'electrodes of the evacuated vessel, .so that $5 approximately similar evacuated vessels may be used in the oscillation generator without producing any change in the high frequency out at. 1

or the accomplishment of this object, this. invention embodies in the output circuit of the oscillating tube a path of high impedance for the direct current from the source of voltage for the output circuit, and a path of, low impedance for the resultant oscillations. The path of high impedance, preferably composed chiefly of a resistance, should be of such a value that the space current remains practically constant irrespective of the conditions of oscillations, and of slight changes of the output voltage source or of the impedance betweenv the output electrodes of the evacuated tube. If the direct current remains constant, it follows,.ther efore, that the alternating current developed will have Specification of Letters Patent.

Patented. June a; 1922.

1917. Serial No. 172,646.

- of constant amplitude may be obtained from this impedance which may be impressed on suitable receiving or transmitting terminals, such as the input circuit'of an amplifier, or the terminals of an outgoing line.

It has also been found that, due to this constancy in the space current, the frequency generated by the oscillator for a given setting of the condenser also possesses the same constancy and is made practically independent of small fluctuations in the voltage or the electrical values of other elements in the circuit.

The output, however, from such a generator is not ure, as high harmonics are present in ad ition to the fundamental oscillation. It is possible to increase the intensity of the harmonics from such a generator to suchan extent that they may be comparable in intensity to the fundamental. This may be accomplished by providing for the high frequency oscillations ofthe generator, a

path, the impedance of which increases with increase of frequency. The drop of potential across this impedance may then be impressed upon suitably tuned circuits, so that the. various harmonics and the fundamental maybe separated from each other.

By the two arrangements described above, vacuum tubes of approximately similar characteristics may be employed in connecchange need be made in the tuning of the circuits, since the frequency will'remain the same. I

' For the better. understanding of this in vention, reference is made to the accompanying drawings, inewhich Fig. 1 r'epresents an embodiment'of this invention from which a constant output may be derived: and Fig. 2 represents an embodiment which may be employed as a harmonic generator. Each evacuated vessel in the drawings has age for said generator, its negative pole be-' ing connected to the filament 11 and its positive pole being connected through the high resistance 13 to the anode 14. This resistance 13 is of such a high value that the direct current flowing therethrough is practically constant and less dependent on the.

frequency of oscillation or on slight changes in the impedance between the output electrodes, orother elements of the vacuum tube circuit. A path of low impedance for the oscillating currents between theanode 14 and the filament 11 is provided by means of the condenser 18 and the resistance 19. The condenser 18 has preferably a large capacity, and has consequently small impedance, so that most of the impedance of this path is due to the small resistance 19. The impedance of this resistance isindependent of the frequency of the oscillations generated, and therefore,-since the space current remains constant, the amplitude of the alternating voltage across the terminals of" this resistance is constant; and. this voltage drop may be employed, as shown, to impress the generated oscillations upon the input circuit 22 of an amplifier 23. The amplified oscillations in the output circuit 24 may by transformer 25 be impressed upon any suitable receiving or transmitting terminals. The amount of voltage impressed on the amplifier may be regulated. by means ofthe adjustable contact 26. This amplifier 23 has the peculiar characteristic that it will allow current to flow through it in one direction only. Consequently, although it functions to-amplify the oscillations from the generator 4 and to impress them upon the outgoing circuit 27, it will not allow current to flow in the opposite direction, that is, from the outgoing circuit back to the oscillator. The outgoing circuit, therefore, cannot react upon the oscillator to produce distortions in the wave form of the oscillations generated due to fluctuations or changes of the load in said circuit.

Condenser 18 is inserted to prevent the-direct current from passing through the side circuit containing the small resistance 19. The source of voltage 10 may be also used as the output battery for the amplifier 23.

A choke coil 28 is preferably inserted to prevent the oscillation currents from passoscillation generator comprising the evacuupon the oscillation generator.

ing through the battery circuit, Similarly, a condenser 29 prevents the direct current from flowing through the primary winding of the transformer 25. r

In Fig. 2, similarto Fig. 1, there is an ated vessel 4, the feed-back connection between the coils 6 and5, and the capacity 7; and across the output terminals of the vefssel is connected the high resistance 13 and the source of voltage 10. A path for the high frequency oscillations is provided by the shunt comprising the inductance 32 and capacity 33 connected across said resistance and source of voltage. The drop of potential across the terminals of inductance 32 is impressed on the input circuit 35 of the unilateral device 36 which is inserted to prevent any reaction of the outgoing circuit The amplified oscillations in the output circuit 38 are impressed, by transformer 39, upon a system I of tuned circuits. Since the impedance of the inductance 32 increases with increase infrequency, it follows that the harmonics generated by the oscillating tube 4 are emphasized considerably more than the fundamental, so that the secondary coil 41 of the transformer 39.contains the fundamental oscillation and its harmonics in approximately the sameorder of intensity. If now the capacity 42 and inductance 43 are of such values that only oscillations of the fundamental frequency f may pass therethrough, then the circuit 45 tuned to the 1 frequency f will receive oscillations of only this frequency by the transformer 46. If the capacity 48 and inductance 49 are tuned to the first harmonic 2, then the tuned circuit 50 will receive oscillations of onl the 105 frequency 2 Similarly the tuned circuit 52 may be made to receive oscillations of only the frequency 3 and so on for other circuits tuned to the higher harmonics. The device, therefore, serves as a harmoniogen- 110 erator, and the harmonics derived therefr'om may be employed for any purpose desired, such as "serving as carrier wave oscillations for low frequency signals in a system for communication. i

Condenser 33 prevents the direct current from the source of voltage 10 from passing through the inductance 32, and the choke coil 54 prevents the generated'oscillations froin .passing' through the path containing 120 the source of voltage 10 and-resistance 13. Condenser 37 is added to prevent the source of voltage 10 from being" short-circuited;

through the primary winding of the transformer 39.

It is evident that the circuit arrangement disclosed in the drawings may be set up for any typ'e of a vacuum tube oscillator desired and then in accordance with this invention tubes of similar structure may be sub: 130

stituted forsthe original tube without disquency oscillations, an outgoin turbing the remaining element of the associated circuits.

What is claimed is: 1. Means for producing oscillations comprising an electric discharge device, a source' of space current for said device, an output; circuit connected to said device for supplying the oscillations produced thereby, said output circuit diaving low impedance for the generated high frequency oscillations and having high resistance for the direct current from the space current source compared with the internal space current resistance of said device, whereby any tendency of the space-current to vary is partially compensated by the variation in direct current voltage across the output circuitand theoscillations produced aremaintained substantiallyv constant inv amplitude irrespective of such tendency.

2. Means for producing oscillations comprising an electricdischarge device, a source of space current for said device, an output circuit connected to said device including a path of high resistance for space currentcompared with the internal output circuit resistance of the device whereby any tendency for variation of the amplitude of the space'current in said path is opposed by the change of voltage across said path to maintain substantial y constant the amplitude of the oscillations produced, a path of low impedance for the. oscillations produced by said means and means for preventing the passage of direct current through 'said low impedance path.

3. An oscillationgenerator comprising an evacuated vessel, a source of voltage for said nerator, apath of high resistance for the irect current from said. source, said resistance having such magnitude that variations occurring in the voltage of said source are not attended with appreciable change in the amplitude of the direct current, a path of low impedance for the generated high frecircuit,

. means for impressingfthe potential difl'er- 'ence set up across said low impedance path upon said outgoing clrcult, said means comprising means whereby said outgoing circuit is prevented from reac'tlng upon said gen.- erator.

4. An oscillation generator comprising an evacuated vessel, a source of voltage for said generator, a path of high resistance for the direct current from said source, said resistance having such magnitude that variations tions, an outgoing circuit, a unilateral device associated with said outgoing circuit and means for impressing upon said unilateral &

device the potential difference set up across said low impedance path.

5. Means for producing oscillations comprising an electric discharge device and a tuned circuit associated therewith, a direct current path connected to the discharge electrodes of said device and including a high resistance of magnitude high with respect to that of the internal resistance of said discharge .device between said discharge electrodes and a source of space current in series, v

lay and two parallel paths connected in the output circult of said relay, one of said paths including a source of space current for said relay in serieswith a resistance of magnitude large with respect to that of the internal space current resistance of said relay and an inductance, and the other of said paths having less inductance whereby the path including the source of space current diverts from the other path a smaller part of the energy of any harmonic frequency oscillations which may be produced by said oscillation-producing means than 'of the fundamental frequency oscillations produced thereby, and means as--- sociated with said other path forselecting therefrom fundamental frequency and harmonic frequency oscillations.

7. Means for producing oscillationscomprising an electric discharge device, a source 7 of space current connected to said device, a high resistance in series with said source whereby the direct, current from said source is made practically independent of slight variations of the voltage of the source, an alternating current path of'low impedance in shunt to the path including said source, said low impedance path containing an inductive reactance, said space current path including a larger inductive reactance whereby the relative amplitudes of the harmonic frequency components to the base frequency components of the oscillations diverted by Said alternating current path are higher than in the total oscillations of the two aths. n

8. eansfor producing oscillations comprising an electric discharge device, a source of space current for said device, a resistance in series with said source of magnitude high with respect to that of the internal space current resistance .of said device so as to keep said output circuit comprising two parallel branches, one of said branches includin a space current source for said device an a resistance in series therewith, said resistance having a magnitude high with respect to the internal resistance of said device so as to maintain the direct current therethrough at substantially the same value irrespective of slight variations of the ratio of the applied space current electromotive force to the impedance of the device whereby the oscillations produced, are maintained substantially constant, and means coupled to the other of said branches for selecting therefrom current of a frequency harmonic to that of the electromotive force impressed upon said input circuit.

10. Means for producing oscillations comprising an electric discharge device having coupled input and output circuits, a source of space current for said device, a resistance in series with said source of a magnitude high with respect to thespace current resistance of said discharge device so as to render the direct current therethrough of substantially the same magnitude for different electricdischarge devices of the same eneral character and impedance connected in the circuit so that the amplitude of'the oscillations generated will not be dependent upon the particular discharge device used, an alternating current path of low impedance also connected to said device, and means for preventing the flow of direct current throu h said path. L

11. cans for producing oscillations comprising an electric discharge device having a cathode, an anode and an impedance COD", trolling element, a source of space current and a resistance connected in series between said anode and cathode of magnitude high with respect to that of the internal resist-' ance of said device between said anode and cathode whereby the direct current is kept substantially constant to hold constant the amplitude of the oscillations produced, and apath of low impedance connected to said high resistance and affordin an alternating current by-pass therearoun for diverting therefrom the harmonic oscillations produced. A

12. Means for producing oscillations comprising an electric discharge device, a source of space current therefor, a direct current path including a resistance in series with said source of magnitude high with respect tive impedances for alternating currents that the low impedance path diverts from the direct current path a larger proportion of. the harmonic frequency oscillations than of the fundamental frequency oscillations and selective circuits associated\with said low impedance path for separating the fundamental and harmonic oscillations produced.

13. Means for producing oscillations com prising an electric discharge device having output and input circuits connected in feedback relation to produce sustained oscillations, a source of space current for said device having a resistance in series therewith of magnitude high with respect to the internal space current resistance of said deviceso as to keep substantially constant the current from said source, an alternating current path shunted around the path including said source and resistance, said alternating current path having an impedance which relatively to the impedance of said shunted path is lower for harmonic frequency currents than for the fundamental frequency oscillations produced, and means connected to said alternating current path for selecting currents of the fundamental and of the harmonic fre- 10 quencies therefrom.

14. Means for producing oscillations comprising an electric discharge device having a space current path including a high resistance element and an alternating current path in parallel said resistance having such magnitude as to render the direct current therethrough of substantially the same magnitude for small variations in the electromotive force of the space current sourcein 110 said space current path, and means to select a currents of different frequencies from saidalternating current path.

15. Means for producing oscillations com- 4 prising an electric discharge device and cir- 11 cuits therefor including a space current path having a high resistance element and analternating current path, said resistance having such magnitude as to render. the direct current therethrough of substantially the series relationship a space current source and a high resistance, an alternating current path in parallel with said v space current path, and means for utilizing the potential set up across a portion of said alternating current path, the resistance of said space current path being high with respect to the internal space current resistance between said cathode and anode so as to swamp the effect upon the value of the unidirectional space current caused by the impedance control element.

17. In combination, two thermionic repeaters each having a cathode, an anode and an impedance control element, one of said repeaters having an output circuit comprising a high resistance space current path and an alternatingcurrent path connected in parallel therewith, the resistance of said space current path being high with respect to the internal resistance of said repeaterfor space current so as to swamp the effect which the impedance control element produces in the value ofthe unidirectional space current, and means connecting the cathode and impedance control element of the other repeater to points in said alternating current path.

18. An oscillator comprising an electric discharge device having coupled output and input circuits, a source of space current for said device, anda resistance in series with said source, said resistance being of such magnitude that the tendencypf variations in the impedance of the device to cause variations in the unidirectional space current is submerged by the effect of the resistance.

19. An oscillator comprisin a thermionic discharge device having coup ed output and input circuits, a space current path for said device including a source of space current and a resistance in series therewith of such magnitude that the tendency of variations in the impedance of the device to cause variations in the unidirectional space current is submerged by the effect of the resistance, and a low impedance path in parallel to said space current path for transferring alternating current energy to a work circuit.

20. In combination, a thermionic repeater having a .cathode, an anode and an impedance control element, an inductance connecting said cathode and said impedance control element, means for impressing across the terminals of said inductance an alternating electromotive force of a fundamental frequency together with its harmonic frequencies, an output circuit connecting said cathode and anode, said output circuit 1neluding a space current path having a resistance of magnitude high with respect to the internal resistance between said cathode and anode, and means associated with said output circuit for selecting therefrom currents of said harmonic frequencies.

21. In combination, a thermionic repeater having a cathode, an anode and an impedance control element, an impedance element, the'impedance of which increases with frequency connecting said cathode and said impedance control element, means for impressing across the terminals of said impedance element an alternating electromotive force of a fundamental frequency together with its harmonic frequencies, an output circuit connecting said cathode and anode, said output circult including a space current path having a resistance of magnitude high with respect to the internal resistance between said cathode and anode, and means associated with said output circuit for selecting therefrom currents of said. harmonic frequencies.

22. A thermionic device having an output circuit comprising a space current path and an alternating current path in parallel, said space current path including a space current source and ahigh resistance in series therewith, said alternating current path including a capacity element and an inductance element in series, and a thermionic repeater having input terminals directly connected to the terminals of said inductance element.

23. A thermionic device having an output circuit comprising a space current path and an alternating current path in parallel, said space current path including a s ace current source, a high resistance, an a large inductance all in series, said alternating current path including a capacity element and a small inductance in series, and a thermionic repeater havinginput terminals directly connected to the terminals of said small inductance element.

24. A harmonic generator circuit comprising an electron discharge device having an input circuit and an output circuit with two parallel branches, one of which branches includes a source of discharge current and a high resistance and the other of which is coupled to a work circuit, said resistance having such a magnitude as to maintain the direct current therethrough substantially constant irrespective of changes in the impedance of. said device.

In witness whereof, I hereunto subscribe my name this 1st day of June, A. D. 1917.

EDWARD 0. SCRIVEN. 

